Printed telephone directory advertising, such as YellowPages, is well known. Such directories normally categorize businesses wishing to be listed, such that a potential consumer can easily peruse all of the businesses within a particular category. More recently, printed telephone directories have been supplemented by directories available on the Internet. In either case, conventional directory advertising systems normally charge businesses according to criteria such as the size, location, and duration of the advertisement displayed. Pricing the directory advertisement in this manner, however, is unrelated to the volume of calls that actually result from the advertisement.